Receiving 2nd place in the Natural Science category of the University of Arkansas Research Symposium!
Author: Rachel Baltz | Major: Biology | Semester: Spring 2024
My name is Rachel Baltz and I am a graduate of the Fulbright College of Arts and Sciences. I have an Honors Biology degree in the Pre-Optometry track, as well as being awarded Magna Cum Laude. My undergraduate research was s in the Biology department under Dr. Christian Tipsmark which occurred in Fall 2022, Spring 2023, Fall 2023, and Spring 2024. This fall, I will attend Southern College of Optometry where I will obtain my OD, and return to Arkansas to spread the message of eye health and care, especially in small towns with little access to such resources.
While my research is in a field that is far from optometry, this year in research has provided me with more opportunities to expand my knowledge than I ever thought possible. Being part of the Tipsmark lab has allowed me to truly understand the research process and what goes on beyond so many lectures. I was able to learn the intricacy of procedures like cDNA Synthesis and Nanodrop testing, as well as the ethics involved with keeping the killifish alive during their long-term acclimation to different salinities. My research will be part of many different scientists’ work as we try to understand just how the phenotypic plasticity works of teleosts such as the killifish. This is an area with generally little that is known, so it is very exciting to know we are all working together to one day be much farther in the knowledge of this and other species.
The topic of my research found me rather than I found it. I met with Dr. Tipsmark in the beginning of my junior year and knew his lab was the best fit for me and what I wanted to get out of a research experiment. Our lab team met many times to go over the basics of the field since I came in with virtually no knowledge on the subject, and over time the topics of gill epithelium and how hormones affect it intrigued me. Atlantic Killifish are a brackish water organism and have the ability to adapt to freshwater or seawater through the changing of different ion transporters and claudins found in many organs, but especially the gills. During my research, I was able to conduct 3 large scale experiments. I was able to report this data at the Arkansas INBRE conference during a poster competition, at the University of Arkansas Research Symposium, and for my Thesis Defense for my biology degree.
My mentor played a large role in becoming successful with this research. Dr. Tipsmark took time out of his busy schedule to train, work together, review papers, have big lab meetings, and schedule occasional checkins to ensure everything was on track. When waves of SURF grant writing or thesis preparation would occur, he prioritized getting our lab to a place that we felt confident in what we were submitting. The Tipsmark lab is a small group, so Dr. Tipsmark was able to provide individual attention to all of our projects and work.
My research specifically focused on Atlantic killifish, an estuarine fish that can handle changes in salinity ranging from dilute freshwater to double strength seawater. To keep constant plasma ion concentrations in a changing environment, specific gill cells secrete salt in seawater and take up ions in fresh water. In fresh water, these ionocytes express Na-Cl cotransporter (ncc) and Na-H exchanger (nhe) that are responsible for NaCl retention, as well as an epithelial calcium channel (ecac) involved in calcium uptake. In seawater ionocytes, Na-K-2Cl cotransporter (nkcc), Na-K-ATPase (nka1a) and cystic fibrosis transmembrane conductance regulator (cftr) are needed to secrete salt. The salinity dependence of the genes was examined in killifish acclimated to fresh water, brackish water, and seawater. A long-term acclimation experiment was conducted by letting fish acclimate to a freshwater, brackish water, or seawater environment. After 3 weeks, the gills were sampled and we tested the DNA to determine the expression of different target genes based on which environment they were found in. Seawater ionocytes were discovered to have a near constant presence in the killifish gill, regardless of if the fish was in an environment where they needed them. Freshwater ionocytes however, were significantly reduced in seawater environments, proving to be only present when the fish needed them. An organ explant experiment examined the role of two osmoregulatory hormones (prolactin and cortisol) in molecular control of gill function. It was discovered that cortisol stimulated both freshwater and seawater ionocytes. Prolactin only stimulated ncc2b, making it a freshwater hormone. We also found that prolactin and cortisol had antagonistic effects on nhe3b, while having synergistic effects on ncc2b. A growth hormone injection experiment occurred where half the fish were injected with growth hormone and half were injected with saline. After 24 hours they were sampled and their DNA was analyzed. It was found that growth hormone aids in seawater tolerance, making it a seawater acclimation hormone. Growth hormone also induced local production of an insulin-like growth factor, which opens the way to a new area of research within the killifish. We also saw an upregulation of nkcc1a. Overall, much was understood involving the molecular pathway and endocrine control of gill ion transport that will hopefully have a place in future research.
This funding helped me in my las semester of undergraduate work. During this busy time of finishing experiments, thesis writing, and general graduation chaos, the funding relieved some of the stress and allowed me to do my best work. The honor of receiving this SURF funding will also help me professionally in years to come. As I enter graduate school, this will be proof that I am capable of rigorous labwork in fields that are constantly discovering new things. It will show my dedication to academic prioritization in my life and that I have a passion for science and the unknown. I hope to go on and enter an optometry lab where I might apply some of the things I have learned in my undergraduate lab. I also will feel confident in applying for grants and other prestigious awards associated with my work because I know what a successful application will look like.
Being part of this lab was incredible, but it did not come without its challenges. I was eager to learn everything I could about the subject, but life kept me from spending every free moment on it. Instead, Dr. Tipsmark and others on the lab team like graduate assistant Karma Hine helped me learn along the way. They would explain how the NKCC transporter worked in the cell or how the pH balancing worked with many ions going in and out through cotransport. There was time made to teach me each step of the testing process and just how to get the perfect 1 microliter pipette. I now feel I have a solid foundation in how to do research with this subject, and now there is much to test. The future is uncertain as to how much of my lab skills I will use again, but I feel confident I will utilize soft skills like the hard work, determination, accuracy, and teamwork in the biology field.